Building

As you can see, the LB000021 has some unpopulated regions on the PCB. We'll be
repopulating the 5V power supply and the USB-ports part.

5V power supply

As you can see, the original 5V power supply consists of quite a lot of parts.
We'll take the dirty hack route here and replace them all with a simple 7805
and a capacitor.
Connect the 7805 to the PCB as seen in the image. The green stuff isn't directly
solderable, you'll have to scrape it off with a knife till you see the copper PCB.
Use an 100uF capacitor to populate C91. Watch out for the polarity of the thing.

USB port

I'll explain how to populate the USB port the farthest away from the Ethernet ports.
If you want to repopulate the other port too, the process is similar.

ID

Part

Remarks

U12

USB connector

R127

Resistor 15K

R128

Resistor 15K

R129

Resistor 22 ohm

R130

Resistor 22 ohm

C94

Capacitor 100uF

L14

-

Shortcut the 2 pads

L15

-

Shortcut the 2 pads

C95

-

Leave open

C96

-

Leave open

48MHz oscillator

The processor'll need a 48MHz clocksignal to time the communication tot the USB-port.
Connect it like this:
Be sure to short-circuit the 2 pads of R16 (unfortunately obscured by the 2 C's on
the photo). Alternatively, put the 1K resistor there.

Hardware: Finished!

Your board now might look like this:

Testing your rig

A few things you might want to check before you plug an USB device into the rig.
Plug in your board and check:

Does smoke come out of anything? That's not what it's supposed to do :)

Does the USB port output 5V?

Is the router reachable on the network?

If you own a scope: Does the oscillator work?

If those points check out ok, you can go ahead and flash an USB-aware firmware
image in the router.